Obturator for firearm adapted to fire caseless or expendable ammunition

ABSTRACT

An obturator for a firearm of the type designed to fire caseless or expendable case ammunition. The obturator can consist of at least two slit metal rings mounted on the bolt head of the firearm and arranged so that the pressure of the expanding propellant gases, generated during firing, compresses the rings so that about zero clearance is maintained around both the inner and outer periphery of the rings. The same type of ring may be used to seal around the firing pin.

United States Patent [1 1 Scanlon Dec. 11, 1973 OBTURATOR FOR FIREARM ADAPTED TO FIRE CASELESS OR EXPENDABLE AMMUNITION [75] Inventor: John J. Scanlon, Monroe, Conn.

[73] Assignee: Remington Arms Company, Inc.,

Bridgeport, Conn.

[22] Filed: June 3, 1971 2i Appl. No.: 149,865

Related U.S. Application Data [63] Continuation of Ser. No. 789,233, Jan. 6, 1969,

abandoned.

[52]. U.S. Cl. 89/26, 277/216 [51]. Int. Cl. F4lc 11/00 [58] Field of Search 89/26; 277/193, 216, 277/217, 218

[56] References Cited UNITED STATES PATENTS 3,166,864 1/1965 Scanlon 89/26 Gerdom 4. 89/26 McGowan 89/26 Primary Examiner-Stephen C. Bentley Attorney-John H. Lewis, Jr. and Nicholas Skovran [57] '7 ABSTRACT An obturator for a firearm of the type designed to fire caseless or expendable case ammunition. The obturator can consist of at least two slit metal rings mounted on the bolt head of the firearm and arranged so that the pressure of the expanding propellant gases, generated during firing, compresses the rings so that about zero clearance is maintained around both the inner and outer periphery of the rings. The same type of ring may be used to seal around the firing pin.

8 Claims, 3 Drawing Figures PAIENIED 1 3,777. 614

Inventordohn d. Scanloh.

Httornqys OBTURATOR FOR FIREARM ADAPTED TO FIRE CASELESS OR EXPENDABLE AMMUNITION This is a continuation of application Ser. No. 789,233, filed Jan. 6, 1969, now abandoned.

This invention relates to an obturator system for firearms of the type used to fire caseless or expendable case ammunition. More particularly, the invention relates to an all-metal ring-shaped obturator which is split so as to compress under combustion pressure to seal the bore of a firearm during firing. A similar obturating system can also be used to seal the opening around the firing pin of such a firearm.

Obturators for firearms designed to fire caseless am munition are shown in U. S. Pats. Nos. 3,166,864 and 3,347,770, issued on Jan. 26, 1965, and Oct. 10, 1967, respectively, to John J. Scanlon, Jr. These obturating systems utilize a rubber or other easily deformable O- ring sandwiched between spiral metal rings.

The advantages and deficiencies 'of caseless and/or expendable cartridges have been discussed at length in previous patents and various publications and need not be repeated here. One of the deficiencies of such firing systems is that with the elimination of the flexible brassor other metallic-cartridge casing, the problem of sealing off the combustion gases is greatly increased. Conventional metallic casings are sufficiently flexible to expand into obturating or gas sealing contact with the walls of the gun chamber upon firing until the pres sure in the chamber is reduced upon the projectile leavingthe bore. With the elimination of this obturating function of the metal casing, it becomes necessary to seal the chamber with the bolt or by some means on the bolt. As the above-cited patents indicate, there have been various attempts made to seal firearms of this type.

Many of the obturating systems proposed are complicated and are difficult and expensive to manufacture. These systems require very precise parts and are designed to seal the bolt only and cannot be utilized to seal the firing pin. Other systems, such as those employing rubber O-rings are short-lived because materials which are suitable for making O-rings do not stand up under contact with combustion gases at high temperatures and pressures.

It lean, therefore, be seen that the primary object of this invention is to provide an obturating system capable of functioning in firearms with caseless or expendable case ammunition which has a longer life than similar systems now known.

It is another object of this invention to provide an ob turating system which is capable of sealing both the bolt and the firing pin against gas leakage when either caseless or expendable case ammunition is used.

Referring to the drawings:

FIG. 1 is a sectional side elevation showing the forward end of the bolt and the firing pin with a round of expendable case ammunition in firing position;

FIG. 2 is a front view of a split metal ring which forms the obturator; and

FIG. 3 shows a side view of the split metal ring of FIG. 2.

In FIG. 1, an elongated barrel is shown having a bore 12 extending longitudinally therethrough. Barrel l0 hasta muzzle end (not shown) from which a projectile 14 mounted in expendable cartridge 16 is explosively expelled and abreech end 18 which is attached to a receiver means 20 in any well-known manner.

Formed in the rear or breech end 18 of the barrel is a firing chamber 22 in which expendable cartridge 16 is slidably positioned and located for firing. Cartridge 16 includes a projectile 14, a molded propellant 24. and a primer 26. Chamber 22 communicates with the barrel bore 12 at its front and with the receiver means 20 at its rear.

Bolt 28 is mounted in said receiver means 20 and is slidably movable to close off the rear or breech end of said chamber. An abutment 30 on the barrel cooperates with an expanded diameter section 32 of the bolt to limit the forward movement of the bolt in said chamber. A reduced diameter portion 34 of the bolt is in sliding engagement with a corresponding portion 36 of the chamber. A second reduced diameter section 38 is formed at the front of said bolt and has an outer peripheral surface 40 which is parallel to and spaced apart from a corresponding inner peripheral wall surface 42 of chamber 22. The space between bolt surface 40 and chamber surface 42 is sealed by obturating gas sealing means 44 which, although disclosing three single-turn back-up rings 46, obviously can utilize less than the three rings shown. A retaining ring 48 is threaded to the bolt head to hold the rings in place.

A firing pin 50 is slidably mounted in the bolt 28 and upon actuation of the trigger mechanism (not shown) on the firearm impacts against the primer 26. A cavity 52 is formed in the bolt 28 to support and guide the firing pin. The cavity is defined an inner bolt peripheral surface 54 which is parallel to and spaced apart from a corresponding outer peripheral surface 56 of the firing pin. This space between bolt surface 54 and firing pin surface 56 can be sealed by a similar obturating gas sealing means 44a. The bolt gas sealing means 44 is supported by an abutment 28a and the firing pin gas sealing means 44a is supported by a back-up member 58 which is rigidly secured to bolt 28.

Since gas sealing means 44 and 44a are substantially alike except for changes in dimension, a description of gas sealing means 44 should suffice for means 44a.

FIGS. 2 and 3 show a single-turn ring 46 made of steel or other suitable material having the necessary wear and temperature resistant properties. Ring 46 has an outer peripheral surface 60 and an inner peripheral surface 62 which engage inner peripheral chamber wall surface 42 and outer peripheral bolt surface 40 respectively.

Obviously, the peripheral surfaces mentioned above have similar surfaces in the bolt-firing pin relationship. Thus, the outer peripheral surface 60a of the ring 46a will engage inner peripheral bolt surface 54 and inner peripheral surface 62a of the ring 46a engages firing pin outer peripheral surface 56. FIG. 3 also shows ring 46 to have a surface area 64 on the side facing toward the firing chamber. In the case of the bolt-chamber sealing means, side surface area 64 is acted on perpendicularly by the combustion gases through retaining ring 48. In the firing pin-bolt sealing means, the combustion gases act directly on the surface area 64a.

A slit 66 cuts entirely through ring 46 to form two unconnected ends 68 and 70. FIG. 3 shows that the slit extends in a plane which is at an angle to surface area 64 thus forming end surfaces 72 and 74, on unconnected ends 68 and 70, which are parallel to and spaced apart from each other by a gap.

Before being assembled into position in the firearm, ring 46 has an outside diameter (shown as O.D. in the drawing) which is greater than the inside diameter of the corresponding portion of the chamber in which the bolt is ultimately slidably positioned. When assembled into position as shown in FIG. 1, the ring 46 is forced in and is compressed whereby the two unconnected ends 68 and 70 approach each other and narrow the gap between them. This results in the ring being biased outwardly so that outer peripheral ring surface 60 engages inner chamber peripheral surface 42 under pressure. At the same time, inner peripheral ring surface 62 fits loosely on the corresponding portion of the bolt and the gap still exists with end surfaces 72 and 74 being spaced apart from each other although not as much as before the ring was assembled into position.

Upon firing, the pressure of the combustion gases acts on side surface area 64either through retaining ring 48 or directly against the ring-to move end surfaces 72 and 74 twoard each other and thus compress the ring inwardly. By compressing the ring inwardly, the biasing force of the bolt against the chamber is relieved to some extent and the loose fitting relationship between the inner peripheral ring surface 62 and. the outer peripheral bolt surface 40 is now changed so that the ring is clamped down against the bolt in gas sealing relationship while the outer ring peripheral surface still is in gas sealing engagement with the chamber.

The inclined slit or gap also facilitates sealing of the slit. Thus, there are three possible ways of the combustion gases escaping past the ring, i.e., between the ring and the chamber wall, between the ring and the bolt, and through the slit. The inclined slit permits the unconnected ring end portions to come together so as to provide a better seal than a straight slit perpendicular to the sides of the ring.

Other advantages will be obvious from the claims.

What is claimed is:

1. In a firearm, a fixed barrel having a firing chamber therein in which is seated a cartridge which is completely consumed or expelled from the gun upon firing, a reciprocal metal bolt closing the breech end of said chamber, at least a portion of said bolt being in slidable engagement with the chamber and having a diameter slightly less than the diameter of the breech end of the chamber, means on said barrel to limit the forward movement of said bolt in said chamber, said bolt having a section of reduced diameter located forwardly of said portion which is in slidable engagement with the chamber, at least one single-turn metal ring positioned on said reduced diameter section of the bolt and having its outer peripheral surface in a biased, pressure-engaging relationship with said chamber prior to firing of the cartridge, slit means extending through said ring to define two unconnected and spaced-apart end portions, and means for radially compressing said slit ring upon firing of the gun into gas sealing position on said bolt while maintaining its gas sealing relationship with said chamber.

2. In a firearm as recited in claim 1 in which said slit means are disposed at an angle to the axial direction of said bolt.

3. In a firearm as recited in claim 2 in which detachable means are provided to lock said ring on the reduced diameter section of said bolt.

4. A firearm for firing a cartridge comprising:

1. a gun barrel having a bore therein through which a projectile is propelled;

2. a receiver means attached to the breech end of the barrel;

3. a firing chamber formed in the breech end of said barrel and communicating with said receiver means;

4. a bolt means mounted so as to move slidably in the breech end of said chamber;

5. a firing pin slidably mounted in said bolt to impact against primer means in a cartridge located in said chamber; and

6. a radially flexible gas sealing ring means positioned on the front of said bolt means rearwardly of said cartridge and biased outwardly against the associated chamber, prior to firing the cartridge,

7. said gas sealing ring means comprising at least one single-turn, metallic, back-up ring having a slit therethrough which is defined by two ring end portions separated from each other by a gap, said ring means upon firing of the cartridge being subjected to direct combustion pressure, means for moving said ring end portions toward each other to provide a close, gas-sealing fit of the inner diametral periphery of the ring on the bolt means while the outer diametral periphery of the ring maintains its gas sealing relationship with said chamber.

5. A firearm as recited in claim 4 in which said slit is angularly directed relative to the longitudinal axis of said bolt means, the dimension of said gap being determined from the relative dimensions of the chamber, the bolt means, and the gas sealing ring means so that upon firing, the inside diametral periphery of the ring will be forced against the bolt while at the same time the outside diametral periphery will still be in gas sealing relationship with said chamber.

6. A firearm as recited in claim 4 in which said slit extends diagonally across the thickness of said ring away from the side of the ring exposed to explosive pressure.

7. A firearm as recited in claim 6 in which detachable means are provided to lock said gas sealing ring means on the front of said bolt means.

8. A gas sealing means for sealing a firing pin which is slidably mounted in a gun bolt, said means comprising at least one single-turn metallic ring which is slit therethrough at an angle so as to provide two unconnected and spaced-apart ring end portions, said slitted ring having an outer diameter which when unstressed is greater than the inside diameter of the corresponding portion of the bolt inwhich said firing pin is slidably mounted, said slitted ring being positioned between said firing pin and said corresponding portion of said bolt so that the outer periphery of the ring is biased outwardly against said bolt and the inner periphery fits loosely on said firing pin, said slitted ring upon firing being subjected to explosive combustion pressure, means for radially compressing said slit ring so that the inner periphery of the ring engages the firing pin in gas sealing relationship while the outer periphery of the ring maintains its gas sealing relationship with the bolt. 

1. In a firearm, a fixed barrel having a firing chamber therein in which is seated a cartridge which is completely consumed or expelled from the gun upon firing, a reciprocal metal bolt closing the breech end of said chamber, at least a portion of said bolt being in slidable engagement with the chamber and having a diameter slightly less than the diameter of the breech end of the chamber, means on said barrel to limit the forward movement of said bolt in said chamber, said bolt having a section of reduced diameter located forwardly of said portion which is in slidable engagement with the chamber, at least one single-turn metal ring positioned on said reduced diameter section of the bolt and having its outer peripheral surface in a biased, pressure-engaging relationship with said chamber prior to firing of the cartridge, slit means extending through said ring to define two unconnected and spaced-apart end portions, and means for radially compressing said slit ring upon firing of the gun into gas sealing position on said bolt while maintaining its gas sealing relationship with said chamber.
 2. In a firearm as recited in claim 1 in which said slit means are disposed at an angle to the axial direction of said bolt.
 2. a receiver means attached to the breech end of the barrel;
 3. a firing chamber formed in the breech end of said barrel and communicating with said receiver means;
 3. In a firearm as recited in claim 2 in which detachable means are provided to lock said ring on the reduced diameter section of said bolt.
 4. A firearm for firing a cartridge comprising:
 4. a bolt means mounted so as to move slidably in the breech end of said chamber;
 5. a firing pin slidably mounted in said bolt to impact against primer means in a cartridge located in said chamber; and
 5. A firearm as recited in claim 4 in which said slit is angularly directed relative to the longitudinal axis of said bolt means, the dimension of said gap being determined from the relative dimensions of the chamber, the bolt means, and the gas sealing ring means so that upon firing, the inside diametral periphery of the ring will be forced against the bolt while at the same time the outside diametral periphery will still be in gas sealing relationship with said chamber.
 6. A firearm as recited in claim 4 in which said slit extends diagonally across the thickness of said ring away from the side of the ring exposed to explosive pressure.
 6. a radially flexible gas sealing ring means positioned on the front of said bolt means rearwardly of said cartridge and biased outwardly against the associated chamber, prior to firing the cartridge,
 7. said gas sealing ring means coMprising at least one single-turn, metallic, back-up ring having a slit therethrough which is defined by two ring end portions separated from each other by a gap, said ring means upon firing of the cartridge being subjected to direct combustion pressure, means for moving said ring end portions toward each other to provide a close, gas-sealing fit of the inner diametral periphery of the ring on the bolt means while the outer diametral periphery of the ring maintains its gas sealing relationship with said chamber.
 7. A firearm as recited in claim 6 in which detachable means are provided to lock said gas sealing ring means on the front of said bolt means.
 8. A gas sealing means for sealing a firing pin which is slidably mounted in a gun bolt, said means comprising at least one single-turn metallic ring which is slit therethrough at an angle so as to provide two unconnected and spaced-apart ring end portions, said slitted ring having an outer diameter which when unstressed is greater than the inside diameter of the corresponding portion of the bolt in which said firing pin is slidably mounted, said slitted ring being positioned between said firing pin and said corresponding portion of said bolt so that the outer periphery of the ring is biased outwardly against said bolt and the inner periphery fits loosely on said firing pin, said slitted ring upon firing being subjected to explosive combustion pressure, means for radially compressing said slit ring so that the inner periphery of the ring engages the firing pin in gas sealing relationship while the outer periphery of the ring maintains its gas sealing relationship with the bolt. 